Display screen or portion thereof with transitional graphical user interface



FIG. 1 is the first image in a sequence for a display screen or portionthereof with transitional graphical user interface showing our newdesign;

FIG. 2 is the second image thereof;

FIG. 3 is the third image thereof;

FIG. 4 is the fourth image thereof;

FIG. 5 is the fifth image thereof; and,

FIG. 6 is the sixth image thereof.

The dashed broken line perimeter in the drawings illustrates a displayscreen or portion thereof and forms no part of the claimed design. Theremaining dashed broken lines in the drawings illustrate portions of thetransitional graphical user interface that form no part of the claimeddesign.

CLAIM The ornamental design for a display screen or portion thereof withtransitional graphical user interface, as shown and described.